Treatment of hydrocarbons



' Patented July 26, 1938 UNITED STATES TREATMENT OF HYDROCABBONS Pike H.Sullivan, New Rochelle, N. 31., assignor to Gasoline Products Company,Inc., Newark, N. L, a corporation of Delaware Application March 21,1933, Serial No. 661,868

4 Claims.

I The present invention relates to an operation for the production of asuperior anti-knock motor fuel product from hydrocarbon materials, andmore particularly relates to the treatment 6 of normallyliquid-hydrocarbon materials of the gasoline type, for example naphtha,gasoline, etc., and normally gaseous hydrocarbon materials, for theproduction of anti-knock motor fuel of the gasoline type. The normallygaseous hydrocar- 10 bon materials may comprise those of thesaturated orparaflin series, such as methane, ethane, propane, butane, pentane, andthe like, or those of the unsaturated type, such as ethylene, propylene,isopropylene, butylene, etc., which are gen- 15 erally designated asolefins.

In the conversion of more or less saturated Y hydrocarbon gases intoliquid products, two distinct types of reactions take place. Thesereactions comprise the splitting or cracking of the saturated moleculesinto unsaturated products such as olefins, and the combination orinterreaction of such unsaturated products for the I formation ofheavier or higher boiling liquid products, respectively.

My invention contemplates subjecting light hydrocarbon oil, such asnaphtha or gasoline of low anti-knock value, to conditions oftemperature and pressure to effect a transformation into constituents ofincreased anti-knock value, commingling the resultant reformed orpartially reformed products with normally gaseous unsaturatedhydrocarbons such as olefins or a gas or gases containing the same insubstantial proportions, subjecting the commingled products to con- 35,ditions of temperature and pressure effective to promote polymerizationof unsaturated hydrocarbons, such as olefins, with or without furtherreforming of the naphtha, effecting inter-reaction or cross reaction(including polymerization) 40 between the more or less unstableunsaturated In the reforming stage of my process, I employ low-boilinghydrocarbon oil, preferably of such character as is ordinarilydesignated as naphtha. Thus, I may employ any virgin or cracked naphtha,or any material having a boiling range within 6 that of the hydrocarbonoils generally designated as naphthas. For example, I may employ an oilconsisting of the heavy ends of the usual naphtha fraction and havingaboiling point range of from 275 to 450 F. 10

While various temperatures and pressures have been proposed and employedfor the reforming of hydrocarbon oils of this character,

' I prefer to .employ temperatures of from 900 F.

to 1000 F., and pressures of from 150 to 1000 pounds per square inch.Thev temperatures may 'be'somewhat lower than those given, for exam.-

ple, approaching 800 F., under a high pressure of, for example, 750 to1000 pounds per square inch or higher, but on the other handhighertemperatures of from 1 0 F. to 1300 F. may be employed with relativellow pressures.

I prefer to limit the time of the initial naphtha-reforming operationprior to the commingling of the treated or partially treated productswith hydrocarbon gases to such extent that a partial reforming effect orconversion is obtained which is somewhat less than the effect ordinarilyobtained, or desired, in reforming operations, in order that theremainder of the reforming or conversion of the naphtha may be carriedout in the presence of the hydrocarbon gases, although I do not limitmyself to any particular extent of reforming prior to the point at whichthe naphtha is commingled with gaseous hydrocarbons.

The normally gaseous hydrocarbons which I prefer to employ are thosegases containing substantial amounts of unsaturated hydrocarbonconstituents, such for example as ethylene, propylene, and otherolefins, The larger the content of such unsaturated hydrocarbons in thegas or gases employed, the moreeflective are the results obtained, butordinarily I prefer to'employ gases containing not less than 10% andpreferably 25% or more of unsaturates.

Certain hydrocarbon gases, for example those gases produced inrelatively high-temperature oil-cracking operations carried out in thevapor phase at temperatures of 1000 F. or higher, ordinarily containlarge amounts of unsaturates and may be employed directly.

However, as indicated hereinabove, I may initially employ gasescontaining only small I amounts of imsaturates or even initially conrtaining substantially no unsaturated constituents, these gases beingsubjected to pyrolysis for the production of unsaturates before beingcommingled with the reformed or partially reformed naphtha. I 7 L Thus,I may employ gases containing'substantial amounts of normally gaseousparaflin hydrocarbons, preferably those containing two or more carbonatoms such as ethane, propane, and butane. Methane, having a singlecarbon atom and being of a comparative refractory nature in so far asconversion to unsaturates is concerned. is less desirable but .may bepresent with other more desirable constituents such as ethane.

As sources of such paraflin'hydrocarbon or other hydrocarbons capable ofconversion to unsaturates such'as olefins, I may employ natural gas orgases derived from the destructive distillation of hydrocarbonmaterials, such as coal and mineral oil I may employ substantially "drygases result ng from the more or less drastic cracking of petroleum oil,or mixtures of liqueflabie hydrocarbons, such for example as "stabilizerreflux containing considerable amounts of butaneand pentane. Ofgasesderived from the decomposition of coal, the so-called"low-temperaturecarbonization coal gas is the most suitable.

When such gases do not contain sufllcient quantitles of unsaturatedgaseous hydrocarbons, they are first subjected as aforesaid to pyrolysisunder elevated temperature for the purpose of increasing their contentof unsaturatedgaseous hydrocarbon materials. The temperatures employedin this gas pyrolysis stage may vary considerably depending uponthenature of the gases being treated. Temperatures of from 1100 to 1750 F.are suitable, but I prefer to employ temperatures of from 1350" to 1600F. The pressure in the gas pyrolysis stage may also vary over a widerange, but in general I prefer to use relatively low pressures of fromatmospheric to 150 pounds per square inch gauge pressure, althoughconsiderably higher pressures may be employed when so desired.

The pyrolyzed gases are then mixed with the products from thenaphtha-reforming stage and the commingled products are digested orreacted under elevated pressure and temperature to promote interreactionbetween more or less unstable constituents, as well as further reformingof the naphtha if desired. .The temperatures and pressures employed inthisdigestion stage may be substantially the same as those -employed inthe 'zone in which the naphtha is subjected to conversion or reforming;however, satisfactory re-- sults may be secured by maintaining in thisdigestion stage temperatures of from about 700 to about 1000 F., and anysuperatmospheric pressure, preferably a pressure of from about 750 toabout 1000 pounds per square inch.

Where they pressure in the gas pyrolysis stage is equal to that employedin the-digestion-stage, the-gaseous products from the pyrolysis stagemaybe delivered directly to the digestion coil or vessel with naphthafrom the reforming stage. ,When the gas pyrolysis pressures are only alittle lower than those which obtain in the reforming stage, thepressure of the products from the ,latter stage'ginay be utilized, asfor example by means of an injector for drawing the pyrolyzed gases intothe digestion stage. Ordinarily however, since it is preferred toconduct the gas pyrolysis at relatively low pressures, and since 1 thetemperatures of the pyrolyzed gasesare quite high, -I prefer to adoptone of two expedients aromas ,or arrest the progress of the conversionof the hydrocarbon gases in such manner as to promote further conversionand reaction in the subsequent digestion stage.

As an alternative expedient, which I prefer to employ when the pyrolyzedgases contain considerable amounts of'normally liquid constituents, thepyrolyzedgases may be cooled to effect the separation of normally liquidconstituents thereof and then raised to the requisite pressure and,preferably after being preheated, are delivered to the digestion stage.

The products from the digestion stage are removed and fractionated torecover valuable light oils such as naphtha or gasoline therefrom. Otherproducts such as fuel oil, gas oil, and heavy naphtha may also berecovered, as well as fixed gas, and all or a portion or portions ofthese may be recycled through the earlier stages of the process forfurther treatment.

In order that'my invention may clearly be set forth and described, I nowdescribe, with reference to the drawing accompanying and forminga partof this specification, various preferred forms and manners in which myinvention may be employed and practiced. In'this The single figure is amore or less diagrammatic view of a system for pyrolytic conversion ofhydrocarbons in accordance with my invention.

Referringnow to the drawing, a low-boiling hydrocarbon oil of thenaphtha or gasoline type, for example an oil consisting of the heavyends of a naphthavfraction derived from a hydrocarbon oil crackingoperation andhaving a boiling-point range of from 300 to,450 F., isdrawn from a suitable source, such as a storage vessel I, and deliveredby means of-a pump 2 through a conduit 3 having a valve l to pipe coils5 and 6 located within a suitable heating furnace structure 1.

During its passage through the coils 5 and 6 the na phtha is subjectedto elevated temperature and pressure conditions to-efi'ect atransformation into constituents of increased antidetonating character,for example, a temperature of about 950 F. and a pressure of from 200 to1000 pounds per square inch.

The reformed or partially reformed products from the coils 5 and 0 passthrough a conduit 8 to a mixer .0, which may take the form of aninjector of conventional type, where they are commingled with normallygaseous hydrocarbons containing unsaturated hydrocarbon constituentsentering the mixer 9 through a conduit Hi. The- .commingled gases andnaphtha then pass through a conduit l2 into a digestion coil l3 wherethey are maintained at reaction temperatures,- of, forexample, from 800to 1000 E, preferably under a pressure-as high as that obtainingin thecoils 5 and 6. The coil [3 may be located, as shown, in a furnacestructure ll when additional heating is required at this point, while onthe other hand the coil l3 may simply be insulated or even cooled whereit is desirable to limit the temperatures in the digestion stage tothose obtaining in the earlier stages or to even lower temperatures.Moreover, in place of the coils l3 the digestion or inter-reaction ofthe commingled gases and naphtha may be accomplished in an enlargedchamber, if desired.

The products from the coil 13 pass through a conduit l6, which may beprovided as shown with a pressure-reducing valve H, to a fractionatingtower 20 which, in the instance illustrated, is provided with baflles2l, trap-out trays 22 and 22a, plates or bubble trays 23 and a coolingor trimming coil 24; It will, however, be obviousto those skilled in theart that the details of the fractionating apparatus mayvary'considerably from the preferred form illustrated in the drawing.

Due to the cooling effect produced by the coil 24 through which iscirculated a suitable cooling fluid, such for example as naphtha to bereformed in the coils 5 and 6, fractionation of the products of reactionfrom the coils l3 takes place in the tower. 20. Relatively heavy oilsuitable for use as fuel oil may be withdrawn from the bottom of thetower through an outlet 26 having a valve 21, while an intermediate outsuch as gas oil may be withdrawn fromthe trap-out tray- 22 through avalved conduit 2811. A, lighter intermediate out, such as insufficientlyreformed heavy naphtha, may be collected on the tray 22a and withdrawntherefrom through a conduit 28. All or any desired portion of thisintermediate cut may be diverted through a branch conduit 31 having avalve 32 and leading to the intake side I of the pump 2. The oil thusdiverted through the conduit 3| is recycled through the coils 5 and 6'for further treatment. All or any desired portion of the stock withdrawnfrom tray 22a may be discharged from the system through a valved line29.

The unoondensed vapors reaching the top of the fractionating tower 20and ordinarily comprising hydrocarbon constituents desirable as motorfuel and having end points as high as from 400 to 430 F., pass througha, vapor line 33 to ing their content of unsaturated hydrocarbon,

such gases are withdrawn from a suitable storage, vessel 50 through a;conduit 5| having a valve 52 and are delivered by a pump 53 to pipecoils 54 and 55 located'within a suitable furnace structure 56. g

In the coils 54 and 55, the gases are brought to suitable temperatureand pressure for the formation of unsaturated hydrocarbons, for examplea temperature of from 1100 to 1750" F. and a pressure of fromatmospheric to 150 pounds per square inch. The pyrolyzed gases may thenpass throu g h a conduit 51 having a valve 58' and the conduit lit foradmixture in the mixer 9 with naphtha from the coils 5 and 6 anddelivery to the digesting coil [3. However, the valve 50 products fromthe coils 54 and 55 contain normally liquid hydrocarbon constituents,the valves 58 and 52 may be closed and the products from the coils 54and 55 may then be withdrawn through a conduit 10 having a valve ll,kept open in this instance, and passed through a heat exchanger 12 and aconduit 13 to a condenser 14. The condenser 14 is provided with a valvedinlet 1'5 and an outlet 16 for cooling fluid such as water. If desired,to check undesired further conversion thereof the hot stream of gasesflowing to heat exchanger 12 may becooled by introducing cold naphtha,or other cool fluid, into the stream of gases by means of the lines 03and 6|, valve 68 being closed and valves 63' and 62 being opened.

The cooled products pass from condenser 14 through a conduit 18 into aseparator 19, from which liquid condensate may be removed through anoutlet line 80 having a valve, 8|, while the unoondensed gaseousproducts pass through a conduit" 82 having a valve 83 to a pump 84 wherethey are compressed and delivered through a conduit 85, the heatexchanger 12, a conduit 80 and the conduit ID to the mixer 9. Y

A portion or all of the gas removed from the separator 38 may bewithdrawn through a conduit 90 having a valve SI and leading to theintake side of the pump 53, by means of which this gas is recycledthrough the pyrolysis .coils 54 and 55. I I

According to my process, a naphtha having an insuflicient anti-knockvalue may advantageously be reformed and converted into a naphthahavtime additional quantities of motor fuel of high ,anti-knock valueare produced through reaction of constituents of the naphtha undergoingreformation with more. or less unstable unsaturatzgd hydrocarbons of anormally gaseous charac r.

While I have indicated that the pressure conditions within thedigestionor reaction-passageway I3 should be as high as those maintainedwithin thenaphtha-reforming coils 5 and 6, it is to be understood thatconsiderably higher operating pressures may be used. Under someconditions of operation it may be found desirable I to employconsiderably higher pressures than those maintained in the coils 5 and6, for example, pressures of the order of from 2000 to '3000 pounds persquare inch within the passageway 13, while temperatures of from about600 F. to about 1100 F. may be employed. Suitable compressing means,such, for example, as that already described for effecting compressionof the gaseous products from the coil or passageway 55, may be employedfor elevating the pressure of the stream of reformed naphtha productsand forcing the same into the passageway l3 under such increasedpressures.

It will be obvious to those skilled in the art that my process issusceptible of considerable modification in detail, and my invention istherefore not limited to the'specific detailsl of the 7 example, orexamples given hereinabove by way of exemplification, but may variouslybe em= bodied within the scope of the claims hereincarbons andsubstantial amounts of higher-boiling constituents to reform saidnaphtha, sub,--'

jecting hydrocarbon gases containing paraflln hydrocarbonconstituentsfree oft-products of combustion to a temperature of from1100' to 1750 F. to promote the formationof unsaturated hydrocarbons,quenching the resultant gaseous products with cool naphtha, comminglingadmixed gaseous products and naphtha with the hot products from saidreforming stage and digesting the cc-mmingledproducts at a temperatureof from 700 to 1000 F. to promote interaction between unsaturatedhydrocarbon censtituentsof said commingled products, withdrawing theresultant products and fraotionating them to recover normally liquidproducts therefrom.

2. The process which, comprises subjecting naphtha to a temperature offrom 900 to 1000 F. in the absence of normally gaseous hydrocarbons andsubstantial. amounts .of higher-boiling constituents to reform saidnaphtha, subjecting hydrocarbon gases containing paraifin hydrocar bonconstituents free of products of comb-ustion to a temperature of from1100 to 1750 F. to promote the'formation of unsaturated hydrocarbons,quenching the resultant gaseous products .with cool naphtha derived fromthe same source as the naphtha being reformed, commingling admixedgaseous products and naphtha with'the hot products from said reformingstage and digesting the commingled products at a temperature of from 700to 1000 F. to promote products therefrom.

ing them to recover normally liquid products therefrom.

3. The process which comprises subjecting naphtha to an elevatedtemperature in the absence of normally gaseous hydrocarbons andsubstantial amounts of higher-boiling constituents to reform saidnaphtha, subjecting hydrocarbon gases containing paraflin hydrocarbonconstit uents free of products of combustion to an elevated temperatureto cheat the formation of unsaturated hydrocarbons "therefrom, quenchingthe resultant gaseous products. with cool naphtha, commingling admixedgaseous products and naphtha with the hot products from said reformingstage and digesting the commingled products at an elevated temperatureto promote interaction between unsaturated hydrocarbon constituents ofsaid commingled products, withdrawing the resultant products andfractionating them to recover normally liquid prcducts therefrom.

4. The process which comprises subjecting naphtha to an elevatedtemperature in the absence of normally gaseous hydrocarbons andsubstantial amounts cf higher-boiling constituents products and naphthawith the hot products from said reforming stage and digesting thecommingled products at an elevated temperature to promote interactionbetween unsaturated hydrocarbon constituents of said commingledproducts, withdrawing the resultant products and fractionating them torecover normally liquid PIKE l-L-SULLJVAN.

